Since 1938 there have been annual breeding studies with corn at this institution and in this contribution to Maize Co‑op News Letter it may be useful for other workers to have a brief history of what we have been doing and what are some of our future aims.
Although corn had been used at the John Innes from time to time for genetical investigations, it was not until C.D.R. Dawson commenced a sweet corn breeding programme just before the war started that corn breeding began here in earnest. As a result of his tests, Dawson released to the seed trade two top crosses, known as the John Innes Hybrids.
However, during the war a number of staff changes took place and a new breeding programme was initiated by K. Mather who found that, owing to the differences in climate of southern England and those States where sweet corn is more commonly grown, even such types as Golden Bantam and Golden Cross Bantam failed to germinate fully here in sowings made before June. The first essential was, therefore, to obtain cold‑hardy lines which would germinate in cold soil. This work has been continued annually, the principle being to breed from plants of different strains which survived February and/or March sowings in the field. On the whole, the results are gratifying and we are now multiplying stocks from our selections of Canada Gold and Golden Early Market. In addition, we hnve a strain of Golden Standard Maize, a dent originally imported from Holland, which has been improved to withstand the rigours of early field sowings.
For several years we have been running an experimental determination of the influence of sowing times on the behaviour of various strains of sweet corn and it now seems likely that sowings earlier than the beginning of June are more advantageous as the seedlings my have a better chance of avoiding frit fly (Orcinella frit) attacks.
Similarly, K. Mather has conducted numerous varietal trials of samples of sweet corn that have reached him from the U.S.A. Numerous crosses have been made and the new combinations tested, but, on the whole, few proved better than the lines we already had. Perhaps because of our cooler climate the ears of the different varieties tested have ripened unevenly, and it was decided that our best chances of producing an improved type of sweet corn for southern England would be to use the methods now so widely established in the U.S.A., namely, to inbreed and select those inbred lines which had the best combining ability later on. A small experiment along these lines was initiated.
Another series of investigations were conducted by A. J. Bateman in his studies of the spatial isolation required by seed crops in order to prevent their contamination with foreign pollen. He used corn as one example of a wind‑pollinated species.
During the last year, through a grant from the Agricultural Research Council, I was able to work with W. R. Singleton at the Connecticut Agricultural Experiment Station so that I could see at first hand the methods of sweet corn breeding practised in New England, and it is hoped to introduce some American methods into our future work at the John Innes. In addition, I was fortunate enough to make a tour of the corn belt and hear some of the current problems of corn geneticists, many of whom have generously supplied lines of sweet corn for our cold‑hardiness experiments.
Our programme for 1948 includes a continuation of the February selections which will include not only the John Innes selected lines, but also a series of inbreds and their hybrids obtained from W. R. Singleton and from the Central Experimental Farm in Ottawa; also a large trial of the stocks I brought back with me to see which behave well enough under our conditions initially before starting our inbreeding campaign and to study the reaction under field conditions of some of my cold‑room selections. Finally we are proposing to see how our previously selected lines behave in various parts of this area of England.